I think it is attached to an engine-start animation. You should create a separate object out of the door and assign the lowest available ID of interior\anim.pmd model. say, it is 35 (1..34 are used by other objects of anim.pmd hierarchy). You put this extra object into the bottom of anim.pmd hierarchy, assign ID = 35 onto it;

then load engine-start animation into tracks editor. add new track into an animation (button on top). set ID = 35 on this track's properties. then toggle free mode and bind your door object with the given track by drag&dropping object from hierarchy window into a tracks editor's window - straight onto a newly-created track. it will show in properties (Controls: door_front, assumgin "door_front" is the object name).

set animation slider to the beginning of the track; drag&drop animation into tracks-editor right-side window; disable & freeze all tracks except the one for the door object (to prevent unintended editing of other "engine-start" animated objects). move/rotate door into opened position and press Set Key button; then move tracks slider to the rightmost position, put the door into closed position and press Set Key again.

save your. z3d file and make a test export of scene; make test export of animation too. test in game.